Secondary batteries are typically used as power sources for portable electronics in view of their high energy density and high voltage. In accordance with the recent size and weight reductions and improvement in the performance of the portable electronics, improvement in the performance and safety of the secondary batteries has come to be increasingly demanded. The use of secondary batteries has spread to large-sized machineries such as electric-powered cars and home electricity storage systems.
Especially, studies on second batteries using a solid electrolyte have been made in view of their enhanced safety and long lifetime. Typically, in order to manufacture the solid electrolyte, Patent Literature 1 exemplarily discloses a method of coating a polymer solid electrolyte on a PET (polyethylene terephthalate) film to form a film of the polymer solid electrolyte. Further, Patent Literature 2 discloses a method of directly coating electrolyte solution on an electrode and heating and drying the coated electrolyte solution. As a further example, Patent Literature 3 discloses a method of casting and drying electrolyte solution on a mold and subsequently heating and pressurizing the electrolyte solution to obtain a film of solid electrolyte.